Simon Chaddock
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Posts posted by Simon Chaddock
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toto
No heating in the man cave?
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Not exactly earth shattering but he V173 does move under its own power and on a "test bed". 😄
https://www.youtube.com/watch?v=DE4uc6giIjQ
The object was to see if it could taxi on a soft surface and not tip over forward with the CG in about the right position.
Unfortunately this test revealed some other serious problems.
The motors do not start well, do not run reliably, can simply stop at high power and further the RH motor produces more thrust then the LH at the same throttle setting. The ESCs have been calibrated.
Not exactly sure why this is happening but I suspect the LH ESC has an "issue" that the RH one does not. I suspect quite a bit of tissue will have to be cut away to replace one or both ESCs.
I did measure the full power amps the 2s battery is supplying just over 7A (60W?) so I would not expect its pair of 10A ESCs to be over stressed.
I shall have to explore a bit further.
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32. made up of 32 that have flown successfully and are still fully complete ready to fly plus one recently complete but not yet flown.
All electric and primarily foam construction.
28 are own design scratch build, four own design power conversions of RTF "chuck" gliders.
Both 35meg Futaba and 2.4 Spektrum.
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PDB
Wow!
That was 10 years ago!
What I was trying to show was that 2mm "original" Depron (but no longer available) due to it having a denser skin on either side was structurally quite close to lightweight balsa but even lighter.
It did fly quite nicely but being so light only in almost still conditions.
I believe it is still in the loft!
Of course I went on to use 2mm and 3mm Depron sheet in bigger RC planes.
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Toto
Lets just hope that when the power does go on it all works correctly!
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Although un flown after some thinking I have decided to modify the V173.
To be honest I was never happy with the inboard tail plane servos having long torque rods although their position was set by the need to include elevator link rods.
The intention is to have a fixed elevator so the servos can be moved outboard & close to the tail plane.
The tissue covered fixed elevator is now just an extension of the body.
There are a couple of videos of RC V173s flying however I note they use quite small props.
This suggests they are actually flying with little or no benefit from the prop wash countering the wing tip losses as Zimmerman intended. In other words they are flying faster to create enough lift despite the inefficiencies of the wing shape.
This very nice scale RC XF5U has even smaller props!
I hope to demonstrate the full "Zimmerman" effect of slow flying without resorting to a "hovering" thrust to weight ratio.
Of course it may not fly at all.
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It is worth noting that the current Depron has a constant relatively fine XPS structure.
The original Depron, now no longer available, had a coarser structure but a shiny denser skin. This made it a true "laminate" so was a good bit stiffer but rather more brittle.
You can just about detect the skin in this blown up "edge" view of original 6mm Depron.
Of course in a 2mm thick sheet this skin made it overall nearly 40% denser than 6mm sheet but it became almost like working in light weight balsa. 😉
As a result it could be used unreinforced even in certain types of a "thin" wing.
All made from original 2mm Depron sheet and nothing else apart from 4 small EDFs, 4 ESCs, a 2200mAh 2s LiPo, 3 micro servos, an Rx and wiring but never to be repeated!!
The 5mm XPS B&Q dark grey and green laminate underlay is cheap but rather flexible with a notably "soft" surface however it is still stiff enough to take a fair proportion of flight loads with only limited reinforcing.
If you are bold enough it can take all the loads. There is no wing reinforcing in this 50mm EDF Hawker Hunter F6 made from the dark grey 5mm XPS.
A bit bigger and lighter than the Nijhuis mini series version.
The wings do bend with g loading but being swept any bending does tend to off load the tips.
Its 3D printed EDF ducting does add some stiffness to the 5mm XPS fuselage.
I am off to B&Q tomorrow to buy a pack of their 3mm white XPS to see if it is suitable for my next plane!
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Surely the quality of buying anything secondhand is down to the purchaser. It is a risk if you rely on the reputation of the seller.
If you fully understand the quality, or not, of what you are purchasing and are satisfied then no problem but if you don't then its a case of "caveat emptor". 😉
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If it was anything like the cold we have had then there is a possibility of condensation in the servo. A 10 degree drop can create a layer of surface moisture even iside an enclosed space.
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Its a bit like the Spektrum/Futaba issue.
Because of past rhetoric feelings are still sensitive.
ps
I currently use two transmitters, a Futaba and a Spektrum. Both are second hand!
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Toto
Nice to have a dog at your feet.
One of ours insists on sitting on my lap. The other insists on sitting in my arms so as to be above and thus "superior" to the one sitting on my lap!
They are fortunately small dogs.
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From what I have read the DVIIi, like the Triplane, relied heavily on the rear fuselage for yaw stability as there is virtually no fixed fin area.
This is made worse by the extended nose on such RC models as the nose extension "eats into" the already limited directional stability.
I also note the prototype DVII had a "short" rear fuselage that at Fokkers insistence was extended secretly by the factory over night despite the fact the plane had been formally submitted to the fighter trials. The resulting control harmony was then considered ideal for a fighter by all the test pilots that flew it.
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I wonder if this is a case of over thinking a problem.
I fly a number of planes "bank and yank" so no rudder. Some have gyros but as there is no rudder the yaw gyro is simply not connected.
In simple terms the gyro has the same control influence as I do. Does it control the plane adequately? It most certainly does.
It reacts to a disturbance so much earlier & faster than I ever can so the effect of the lack of yaw input never develops to the point where I can visually react to it.
I would suggest that if a plane has no ailerons then simply don't connect the roll gyro. It will still "manage" control better than a human.
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Quote
Wrong in so many ways.
Care to explain?
According to the IEE regulations there is no limit on the number of sockets on a ring main.
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Toto
I appreciate that you are likely to only plug relatively low power items but I assume your ring main feed has a 32A circuit breaker protection for safety.
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Here is it now complete and painted with new nose no2.
With a wing loading just under 4oz/sqft I will definitely wait for the right (no wind) conditions to test it.
In the mean time at least I won't have to look at it hanging on the wall in a damaged state!☺️
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The model "flying" picture I am most proud of is now quite old and of rather poor quality as its a still from a video.
Nevertheless it could almost be a shot from a Concorde "display" pass rather than of a 36" span lightweight EDF built entirely from 2mm Depron sheet.
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The story was the new nose did not last long! From a low level stall I did exactly the same thing so no nose again.☹️
It been hanging on the wall like this for 5 months. A benefit with these Depron planked structures they "crumple" so there is virtually no damage to the rest of the air frame.
Having virtually completed the Vought V173 I took pity on the Skyray so started a new nose.
As before PLA printed formers. Quick to do with the advantage that new nose will be the same as the previous one.
Actually with an all planked structure PLA formers are not ideal as unlike a Depron former it is not possible to pin each plank to the former as each has to be taped in place meaning the next plank cannot be fitted until the glue has dried sufficiently.
Rater than build over the plan this time I cut out a foam center line "blank" that matched the fuselage profile and glued the formers to it to allow the planking process to begin.
The C/L blank will be cut away once the planking is complete.
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As the forecast suggested the calm all over grey is soon to end I flew both versions of my F707 "chuck glider" RC conversions. Being light they thrive in calm conditions.
AET basic. 1200mm span. 320g with an 850mAh 3s.
AET + flaps. 344g with a 1500mAh 2s.
Both fly very nicely. With 3 settings (0,15,40 degrees) the flapped version is more interesting to fly although the "basic" has a noticeably better glide ratio.
Not long after I finished it started to rain!
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Flying daddy
You need to be careful.
"Instant" electric flying as it is so quick and easy can get you in a state of mind along the lines of "I know it will fly so I'll not bother and anyway its cold outside"!
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After a light coat of Eze Dope the V173 gets a coat of "Banana Split" emulsion, courtesy of Dulux, watered down by 20%.
Just a thin coat to keep the weight down but it is still very yellow. 🙂
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A start on the tissue covering. I have just about enough Model Span left over from many years ago when I last tissue covered anything!
Underside/
Top side
Quite a bit of double curvature so each surface needed several pieces.
Only water spray shrunk at the moment but will be Eze Doped before painting.
The battery hatch will use the very last bit of my true 2mm Depron sheet. 😥
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To solve that problem what you would need is an "air to air" heat exchanger or in other words an air conditioning system!
Cool the air going out and transfer that heat to the air coming in but not easy to do economically at the low temperature differences involved.
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The extreme "stalky" undercarriage.
Not scale just simple braced wire both to have plenty of "give" and to save weight. As are the LW-PLA wheels!
The ground angle suggests the initial tests once the tail lifts a bit will be no mote than low power hops.
Exactly where the CG needs to be will be a case of battery placement trial and error. The battery compartment was left long to allow for this.
Now all the electric are in and tested a start can be made on the tissue covering.
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Aileron differential all up & NO down?
in All Things Model Flying
Posted
I am a bit concerned at the comparison to original WW1 panes. Most RC models are aerodynamically quite a bit different. Just look at the wing sections used.
The only issue with all up and no down is the amount of yaw caused when full aileron is applied. Excessive yaw in turn will cause the nose to drop which can be a problem with a panic aileron input if low and slow. 😉
As a regular "bank and yank" flyer using aileron differential I can only add that as with any control surface set up It is important to understand what is the cause of what is happening and recognise it may take some trial and error adjustment to arrive at flight characteristics that you are happy with.